Myasthenia gravis is an autoimmune disease that causes dysfunction of the neuromuscular synapses. Seventy percent of patients with myasthenia gravis carry autoantibodies to the acetylcholine receptor (AChR) and a separate 10% carry autoantibodies to muscle specific tyrosine kinase (MuSK) (Vincent and Leite, 2005, Curr Opin Neurol; 18(5):519-25). However, twenty percent of patients with myasthenia gravis are seronegative for autoantibodies to AChR and MuSK. Thus, there is a need for improved diagnostic and treatment methods for neuromuscular disorders such as myasthenia gravis.